html,
body {
  margin: 0;
  padding: 0;
  background-color: #f3f3f3;
}
header {
  width: 100%;
  height: 2.2rem;
  position: fixed;
  display: flex;
  top: 0;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  background-color: #f8f8f8;
  box-shadow: 0 2px 4px #b3b3b3;
  border-bottom: 1px solid #f6f6f6;
  color: #333333;
}
.content {
  height: 83%;
  overflow-y: scroll;
  margin-top: 2.3rem;
  margin-bottom: 1rem;
}
.content .systemInfo {
  width: 8.8rem;
  color: #aaa;
  padding: 5px;
  text-align: center;
  font-size: 0.6rem;
  background: #e3e3e3;
  border-radius: 4px;
  margin: 0 auto;
  margin-top: 10px;
}
.content .subInfo {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}
.content .subInfo .nickname {
  font-size: 0.6rem;
  color: #999;
  margin-bottom: 4px;
  margin-left: 10px;
}
.content .box {
  display: flex;
  width: 90%;
  margin: 0 auto;
  padding-top: 1rem;
  align-items: center;
}
.content .box .avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  overflow: hidden;
}
.content .box .msg-box {
  padding: 5px 10px;
  padding-bottom: 10px;
  height: 1.2rem;
  border-radius: 5px;
}
.content .box .image-box {
  padding: 5px 15px;
  width: 110px;
}
.content .right-box {
  flex-direction: row-reverse;
}
.content .right-box .msg-box {
  background-color: #e05c5c;
  color: white;
  margin-right: 10px;
}
.content .left-box {
  flex-direction: row;
}
.content .left-box .msg-box {
  background-color: white;
  margin-left: 10px;
}
footer {
  position: fixed;
  bottom: 0;
  height: 3rem;
  background-color: #f2f2f2;
  border-top: 1px solid #e3e3e3;
  width: 100%;
  display: flex;
  flex-direction: row;
  justify-content: space-around;
  align-items: center;
}
footer .input-box {
  width: 68%;
  border-radius: 0.6rem;
  border: none;
  outline: none;
  height: 1.8rem;
  margin: 1rem 0;
  padding-left: 1rem;
  font-size: 1rem;
}
footer .input-box:focus {
  caret-color: #317EF3;
}
footer .send-btn {
  background-color: #e05c5c;
  border-radius: 0.5rem;
  width: 20%;
  color: white;
  border: none;
  outline: none;
  padding: 0.4rem 0;
  margin: 1rem 0;
}
footer .send-btn:hover {
  background-color: rgba(224, 92, 92, 0.6);
}
@media (min-width: 500px) {
  body {
    background-color: white;
    width: 100%;
    height: 100vh;
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
  }
  .container {
    width: 500px;
    height: 83%;
    background-color: #f3f3f3;
    position: relative;
  }
  header {
    width: 500px;
    top: auto;
  }
  footer {
    position: absolute;
    bottom: 0;
    width: 500px;
  }
}
